Coherent Population Trapping on the Second Resonance Line of Potassium

We present the observation of coherent population trapping resonances on the second resonance line of potassium: 4s2S1/2 -> 5p2P3/2 with wavelength of 404.4 nm. Moreover, a transfer of the coherent population trapping resonance occurs to the excited 4p2P1/2 and 4p2P3/2 states of the first resonance line due to cascade transitions. This transfer is evidenced by the observation of narrow resonances at the infrared 4s2S1/2 -> 4p2P1/2 and 4s2S1/2 -> 4p2P3/2 transitions when alkali excitation is performed at the 404.4 nm violet line.